The present invention relates to a side airbag apparatus that protects an occupant seated in a vehicle seat from an impact by deploying and inflating an airbag on a side of the occupant when an impact is applied to a vehicle.
A side airbag apparatus having an airbag and an inflator is widely known for protecting an occupant from an impact when the impact is applied to an automobile from a side to an automobile seat in which the occupant is seated, for example, due to a side collision. In the side airbag apparatus, an airbag is installed in a seat back of an automobile seat in a folded state together with an inflator. The outer shape of the airbag is formed by an airbag main body.
In the side airbag apparatus, when an impact is applied from the side on a side wall portion of an automobile body such as a side door, inflation gas is supplied from the inflator into the main body of an airbag, so that the airbag main body is deployed and inflated. The airbag is projected from the automobile seat with a part of the airbag remaining in the seat back. Thereafter, the airbag main body is deployed and inflated forward in a narrow space between the upper body of the occupant and the side wall portion. The airbag main body is located between the occupant and the side wall portion, which bulges inward, to restrain the occupant and reduces the impact from the side transmitted to the occupant via the side wall portion.
In the human body, the lumbar region and the shoulder region are generally known to have a better impact resistance than the thorax. Therefore, in the case of a side airbag apparatus that protects an occupant in a large area ranging from the lumbar region to the shoulder region, it is preferable that an airbag main body protect the thorax by softening the impact to thorax more than the impact to the lumbar region and the shoulder region.
In this connection, Japanese Laid-Open Patent Publication No. 2010-137615 discloses a side airbag apparatus that has an airbag main body divided into a plurality of inflation chambers. The inflation chambers are each inflated with an internal pressure appropriate for the impact resistance of the side of the occupant. In the side airbag apparatus, an airbag main body 131 is divided into a first inflation chamber 134, a second inflation chamber 135, and a pair of upper and lower third inflation chambers 136, 137 as illustrated in FIG. 31. The second inflation chamber 135 is located in front of the first inflation chamber 134 with a vertical partition 138 in between. The third inflation chamber 136 is located above the first inflation chamber 134 and the second inflation chamber 135 with a lateral partition 139 in between. The third inflation chamber 137 is located below the first inflation chamber 134 with a lateral partition 141 in between.
The vertical partition 138 is formed by an inner tube encompassing the inflator 133. The vertical partition 138 has an opening 142, which connects the first inflation chamber 134 and the second inflation chamber 135 with each other. The upper lateral partition 139 has an opening 143, which connects the first inflation chamber 134 and the third inflation chamber 136 with each other, and a check valve 144, which prevents inflation gas in the third inflation chamber 136 from flowing back to the first inflation chamber 134 through the opening 143. The lower lateral partition 141 has an opening 145, which connects the first inflation chamber 134 and the third inflation chamber 137 with each other, and a check valve 146, which prevents inflation gas in the third inflation chamber 137 from flowing back to the first inflation chamber 134 through the opening 145.
According to the above described side airbag apparatus, part of the inflation gas discharged forward from the inflator 133 is supplied to the first inflation chamber 134. The part of the inflation gas is supplied to the second inflation chamber 135 through the opening 142, and other part of the inflation gas is supplied to the third inflation chamber 136 through the opening 143 and the check valve 144. Part of the inflation gas discharged downward from the inflator 133 is promptly supplied to the third inflation chamber 137 through the opening 145 and the check valve 146. Further, the check valves 144, 146 prevent the internal pressures of the first inflation chamber 134 and the second inflation chamber 135 from being excessively increased at the restraint of the occupant. Also, the internal pressures of the third inflation chambers 136, 137, which have been raised to level appropriate for protecting the shoulder region and the lumbar region, are maintained.
In this manner, the third inflation chambers 136, 137 are deployed and inflated with high internal pressures beside the shoulder region and the lumbar region, which have a high impact resistance, and the first inflation chamber 134 and the second inflation chamber 135 are deployed and inflated with low internal pressures beside the thorax, which has a low impact resistance. Thus, the airbag main body 131 is deployed and inflated with a pressure distribution appropriate for the impact resistance of the side of the occupant, so that the shoulder region, the lumbar region, and the thorax are effectively protected from an impact.
In the side airbag apparatus in the above document, part of the inflation gas discharged forward from the inflator 133 is promptly supplied to the second inflation chamber 135 through the opening 142, so that the second inflation chamber 135 is deployed and inflated in the vicinity of the side of the thorax. The supply of inflation gas to the third inflation chamber 136 is delayed due to the supply of inflation gas to the second inflation chamber 135. This possibly causes a delay in restraint and protection of the shoulder region of the occupant.
Accordingly, it is an objective of the present invention to provide a side airbag apparatus that is capable of promptly supplying inflation gas to the portions of an airbag that are inflated beside the shoulder region and the lumbar region of the occupant.